[query] Add ability to set default query timeout

src/cmd/services/m3query/config/config.go

@@ -58,6 +58,8 @@ const (
 	errNoIDGenerationScheme            = "error: a recent breaking change means that an ID " +
 		"generation scheme is required in coordinator configuration settings. " +
 		"More information is available here: %s"
+
+	defaultQueryTimeout = 30 * time.Second
 )
 
 var (
@@ -125,6 +127,9 @@ type Configuration struct {
 	// Carbon is the carbon configuration.
 	Carbon *CarbonConfiguration `yaml:"carbon"`
 
+	// Query is the query configuration.
+	Query QueryConfiguration `yaml:"query"`
+
 	// Limits specifies limits on per-query resource usage.
 	Limits LimitsConfiguration `yaml:"limits"`
 
@@ -188,6 +193,19 @@ type ResultOptions struct {
 	KeepNans bool `yaml:"keepNans"`
 }
 
+// QueryConfiguration is the query configuration.
+type QueryConfiguration struct {
+	Timeout *time.Duration `yaml:"timeout"`
+}
+
+// TimeoutOrDefault returns the configured timeout or default value.
+func (c QueryConfiguration) TimeoutOrDefault() time.Duration {
+	if v := c.Timeout; v != nil {
+		return *v
+	}
+	return defaultQueryTimeout
+}
+
 // LimitsConfiguration represents limitations on resource usage in the query
 // instance. Limits are split between per-query and global limits.
 type LimitsConfiguration struct {

src/query/api/v1/httpd/handler.go

@@ -22,7 +22,6 @@ package httpd
 
 import (
 	"encoding/json"
-	"errors"
 	"fmt"
 	"net/http"
 	_ "net/http/pprof" // needed for pprof handler registration
@@ -121,15 +120,11 @@ func NewHandler(
 
 	handlerWithMiddleware := applyMiddleware(r, opentracing.GlobalTracer())
 
-	var timeoutOpts = &prometheus.TimeoutOpts{}
-	if embeddedDbCfg == nil || embeddedDbCfg.Client.FetchTimeout == nil {
-		timeoutOpts.FetchTimeout = defaultTimeout
-	} else {
-		if *embeddedDbCfg.Client.FetchTimeout <= 0 {
-			return nil, errors.New("m3db client fetch timeout should be > 0")
-		}
-
-		timeoutOpts.FetchTimeout = *embeddedDbCfg.Client.FetchTimeout
+	timeout := cfg.Query.TimeoutOrDefault()
+	if embeddedDbCfg != nil &&
+		embeddedDbCfg.Client.FetchTimeout != nil &&
+		*embeddedDbCfg.Client.FetchTimeout > timeout {
+		timeout = *embeddedDbCfg.Client.FetchTimeout
 	}
 
 	return &Handler{
@@ -144,14 +139,16 @@ func NewHandler(
 		embeddedDbCfg:         embeddedDbCfg,
 		createdAt:             time.Now(),
 		tagOptions:            tagOptions,
-		timeoutOpts:           timeoutOpts,
 		enforcer:              enforcer,
 		fetchOptionsBuilder:   fetchOptionsBuilder,
 		queryContextOptions:   queryContextOptions,
 		instrumentOpts:        instrumentOpts,
 		cpuProfileDuration:    cpuProfileDuration,
 		placementServiceNames: placementServiceNames,
 		serviceOptionDefaults: serviceOptionDefaults,
+		timeoutOpts: &prometheus.TimeoutOpts{
+			FetchTimeout: timeout,
+		},
 	}, nil
 }